Substrate utilization in porcine embryos cultured in NCSU23 and G1.2/G2.2 sequential culture media

Embryo metabolism is an indicator of viability and, therefore, efficiency o f the culture medium. Currently, little is known regarding porcine embryo m etabolism. The objective of our study was to evaluate glucose and pyruvate uptake and lactate production in porcine embryos cultured in two different media systems. Oocytes were matured and fertilized according to standard pr otocols. Embryos were allocated randomly into two culture treatments, NCSU2 3 medium or G1.2/G2.2 sequential culture media 6-8 h post-insemination (hpi ). Embryo substrate utilization was measured at the two-cell (24-30 hpi), 8 -cell (80 hpi), morula (120 hpi), and blastocyst (144 hpi) stages using ult ramicrofluorimetry. Glucose uptake was higher (P < 0.05) in two-cell embryo s cultured in G1.2 than in NCSU23 medium (4.54+/-0.71, 2.16+/-0.87 pmol/emb ryo/h, respectively). Embryos cultured in G1.2/G2.2 produced significantly more lactate than those in NCSU23 at the eight-cell stage (9.41+/-0.71, 4.4 2+/-0.95 pmol/embryo/hr, respectively) as well as the morula stage (11.03+/ -2.31, 6.29+/-0.77 pmol/embryo/hr, respectively). Pyruvate uptake was highe r (P < 0.05) in morula cultured in G1.2/G2.2 versus NCSU23 (22.59+/-3.92, 1 1.29+/-1.57 pmol/embryo/h, respectively). Lactate production was greater (P < 0.05) in blastocysts cultured in G1.2/G2.2 (38.13+/-15.94 pmol/embryo/h) than blastocysts cultured in NCSU23 (8.46+/-2.38 pmol/embryo/h). Pyruvate uptake was also greater in blastocysts cultured in G1.2/G2.2 (24.3+/-11.04) than those in NCSU23 (11.30+/-2.70). When cultured in NCSU23 medium, two- and eight-cell embryos utilized less glucose than morulae and blastocysts, and two-cell embryos produced less lactate than blastocysts (P < 0.05). In G1.2/G2.2 media, two-cells took up less pyruvate than morulae or blastocyst s, while blastocysts produced more lactate and utilized more glucose than t wo-cell, eight-cell and morula stage embryos (P < 0.05). As in other specie s, glycolysis appears to be the-primary metabolic pathway in post-compactio n stage porcine embryos. Culture medium composition affects not only substr ate uptake, but also metabolic pathways by which these substrates are utili zed in porcine embryos at several developmental stages. (C) 2001 Wiley-Liss , Inc.